A critical biography of the engineer Wernher von Braun (1912-1977) by the journalist Jacques Ahrweiler. The book traces his path from his origins as a Prussian baron and his enthusiasm for rocketry in Weimar Germany, through his recruitment by the German army in 1932, the development of the V-2 at Peenemünde (built with concentration-camp slave labour at the Mittelwerk-Dora), his 1945 surrender to the Americans (Operation Paperclip), and his career at NASA up to the Apollo program. Three appendices (« Rockets », « Moralities », « The supplement of science ») extend the narrative into a reflection on the responsibility of the scientist. Paperback edition in the « Événements » series.